Brakes - caliper won't wind back

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Dollywobbler
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Brakes - caliper won't wind back

Post by Dollywobbler »

A lovely day for overhauling the BX's brakes. Pads almost down to the metal one side, binding caliper the other. Rather worried to discover that neither inner pad has the necessary pips on it...

The slider boots seem a little loose on both sides - pushing the caliper to its limits uncovers the slider. I've covered them in heat-proof grease as much as I can and I don't think they'll be exposed when the pads are in place.

One side completed. No problems. However, the other side is proving a pain. I just can't wind the piston back enough to get the new pads in. Handbrake cables are naturally disconnected and I'm levering the other side of the caliper as you should. It has wound back a certain amount, and it wound out nicely until I realised I was turning it the wrong way...

My emergency answer to get the car mobile again is to just chuck in the pads that I took out - they're barely worn on the passenger side. Slightly concerned about this odd mix of pads - the nearside one has been binding anyway. I've also got a bit of disc inbalance - nearside looks almost new, offside is aged and quite rusty around the edges with a slight wear lip. Decided they aren't bad enough to replace yet but the unusual difference side to side is most peculiar.
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JayW
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Re: Brakes - caliper won't wind back

Post by JayW »

Sounds like corroded bores, quite common at the age of these, particularly if LHM changes have been neglected or it's been left unused for some time.

The other likely alternative is the handbrake pinion sticking but i'd be more inclined to go for the former if you think the HB mech is free.
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Re: Brakes - caliper won't wind back

Post by Dollywobbler »

Well, putting more rearward pressure on it seemed to work. Might need to slacken both handbrake cables though as the lever barely moves at all - or is this the handbrake nirvana BX owners dream of? Still comes up a few clicks so perhaps I'll do a road test and see how things are. I've done a static test with it on ramps. Wheels turn easily by hand - that wasn't true of the nearside one before I started this job.
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Re: Brakes - caliper won't wind back

Post by KevR »

If the inner pads don't have the pips on then the caliper will just wind itself up to the point that the brakes are binding all the time and probably end up locking on. I've had this happen within forty miles of fitting new pads without the pips.
I think the 'pipless' pads are designed to fit a Renault Express but are often sold as BX pads because the shape's the same.
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Re: Brakes - caliper won't wind back

Post by Dollywobbler »

Thankfully, that hasn't happened. I've done over 1500 miles in it now! Test drive suggests all is well.
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Way2go
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Re: Brakes - caliper won't wind back

Post by Way2go »

KevR wrote:If the inner pads don't have the pips on then the caliper will just wind itself up to the point that the brakes are binding all the time and probably end up locking on.
I don't think the locking on is a natural consequence as the hydraulics will always back off fractionally if the pistons are clean BUT they will be constantly rubbing and you will find that the inside one will become worn down faster while the outside one has plenty of meat on it. I know this sounds funny given the slider but probably just because of the inertia in the slider.
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KevR
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Re: Brakes - caliper won't wind back

Post by KevR »

When I fitted pads with no pips they definitely rubbed to the point of near seizure, which I put down to the auto-adjuster for the handbrake winding itself up. Could be wrong, but it put me off the idea big time!
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!
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Re: Brakes - caliper won't wind back

Post by Way2go »

Don't get me wrong, I wasn't advocating that pips aren't neccessary. I would never use pads without pips again, you can hear the periodic rub of the pads with the windows open when crawling in slow traffic. I fact I replaced them with pipped ones before the end. (replaced the discs at this point too)
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Re: Brakes - caliper won't wind back

Post by Way2go »

Further thought, If the pads are constantly tight, apart from poorer mpg results they will heat the hub possibly to the point of losing grease from the hub bearings with resultant failure there. :(
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Re: Brakes - caliper won't wind back

Post by Dollywobbler »

Yup. Very possible. Indeed, there did look to be some grease trails from the nearside hub. Brand new hub nut, so guessing it wasn't that long ago that the bearing was changed. Had a REALLY bad binding brake on a Saab 900 once. I noticed because so much grease had been lost that the bearing developed play and I got wheel wobble.
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